Messages in this thread |  | | Subject | Re: [alsa-devel] [PATCH linux-next v2 9/9] ASoC: rsnd: add busif property to dai stream | From | Jiada Wang <> | Date | Thu, 4 Oct 2018 16:00:24 +0900 |
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Hi Morimoto-san
Thanks for your comments
On 2018/10/04 12:43, Kuninori Morimoto wrote: > Hi Jiada > > Thank you for your feedback > >>>> in GEN3 SSI may use different BUSIF for data transfer, >>>> this patch adds busif property to each dai stream, >>>> to indicate the BUSIF used by playback/capture stream. >>>> >>>> Also adds rsnd_ssi_select_busif() to automatically select >>>> BUSIF (currently only BUSIF0 is selected) >>>> >>>> Signed-off-by: Jiada Wang <jiada_wang@mentor.com> >>>> --- > (snip) >>> And this patch selects it on runtime (= hw_param) ? >> Because, in order to automatically determine BUSIF number, >> information like SSI mode (non-Split/Split/Ex-Split), runtime channel, >> are required >> (in our internal implementation, SSI mode is selected by kctrl) >> because of this, in this patch, BUSIF is selected on runtime >> >>> But, I think we can/should select it on probe timing from DT connection. >>> Am I misunderstanding ? >> with the above reasoning, BUSIF is selected on runtime. >> what do you think? > I have no objection that you are customizing your kernel locally. > But, upstreaming kernel based on it is not acceptable for me. > I'm not sure detail of your local implementation, but I don't think we > need to select SSI mode by kctrl. > If my understanding was correct, it can also be selected automatically somehow. > Or, am I misunderstanding ? SSI can work in following modes 1. Basic Mode: (channel 1, 2, 4, 6, 8, 16) 2. TDM Extended Mode: (channel 6, 8) 3. TDM Split Mode: (channel 1, 2) 4. TDM Ex-Split mode: (Channel 2, 4, 6, 8, 10)
for example user asks dai-link0 to playback 2ch audio stream, driver can't determine which mode to work, as it can be Basic mode, Split mode or Ex-Split mode.
> I could understand what you want to do, and yes, I can agree that we want/need > to have it on upstream. Thank you very much to indicating it to me. > But we need to consider more how to implement it. > Especially, it is related to DT bindings. > As you already know, if it is implemented on upstream kernel, we need to keep > compatibility in the future, and it is very difficult. Yes, I agree with you, upstream need to consider lots of things > > So, my opinions for BUSIFn support are > - SSI mode should be selected automatically can you give me your idea, how to automatically determine working mode, when user plays 2 channel stream on playback dai-link > - BUSIFn connection should be selected on DT since which BUSIFx is used during audio data transfer, is not consideration of user, I think your previous suggestion, (automatically select BUSIFx) makes more sense
Thanks, Jiada > (I think we don't want random sound output position ?) > - To select it, we need to have new "ssiu" DT seetings, > or parse sound card. Maybe adding ssiu is realistic. > > > Best regards > --- > Kuninori Morimoto
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